Gary Neville's brief spell as Valencia manager is at risk of coming to a premature end unless his team can win against fellow strugglers Real Betis on Sunday.

The English coach faced stinging criticism from club legends David Albelda and Santiago Canizares after his side were thumped 7-0 by Barcelona in a Copa del Rey semi-final tie.

"Valencia's defeat is the worst I can ever remember. I expected him to resign there and then and to apologise," Canizares wrote on Twitter. "Perhaps I'm ignorant but I'm surprised he didn't resign. I thought he was an honest man."

Valencia-born Albelda, meanwhile, claimed Neville did not take the club's downfall seriously, and that he was only still in the job because of his friendship with Singaporean owner Peter Lim.

"Neville feels strong because Valencia is owned by a man from Singapore who gave him the job," said the former midfielder, who was club captain for a decade. He has turned up and hasn't changed the system nor the players and the results are even worse. He doesn't give any importance to Valencia's run, which is the worst in the club's history."

The former Manchester United defender was also shown little mercy by the local press. He receives a translated round-up of the Spanish sports press in his inbox every morning at 9am, but one newspaper headline required little instruction. "Historic humiliation" was how 'SuperDeporte' described Valencia's limp display at the Nou Camp. Above the headline were five words, each separated by a bullet point. "Ruin", "Disgrace", "Unworthy", "Unacceptable", and "Insulting". 'Marca' was not much kinder, going with "Seven Goals and a Funeral".

Neville witnessed the supporters' livid reaction to the club's worst defeat in the cup for 88 years when his team returned to their Paterna training ground at 2.30am to be met by 300 indignant fans chanting "mercenaries". And for the first time he heard supporters chant the fateful words "Neville vete ya", the universal call in Spain for a manager to be sacked, a refrain heard particularly often at Valencia.

Even the official club media was up in arms, tweeting: "Dear supporters, you do not deserve such a painful night as this. Thanks for your support, there are no excuses."

The usually radiant Neville cut a sad figure in the press room of the Nou Camp, a stadium which holds glorious memories for the former United defender. "I stood out there feeling helpless, trying to change it in some way, knowing the tide of the game was against us," he said. "Positivity has been immovable in my life but when I have moments like this I don't enjoy them at all, it was painful."

Neville refused to answer repeated questions from Spanish journalists about his future but must know his position is under serious threat unless his team win at Betis.

Like Betis, Valencia now face a battle to avoid relegation, a scenario few would have believed possible when Neville took over at the start of December, with the team just five points off the Champions League places. Eight games without a league win later, they are five points above the relegation zone. There is a feeling that Neville is not to blame for the predicament, but was never the right man for this job.

"Neville could well be a great coach, he is proper football man, but this Valencia side, which is so young, needs a proper, experienced coach to lead them out of this situation," says journalist Conrado Valle.

"It is not that he has made mistakes, but he hasn't been able to change the team's dynamic."

Neville has made every effort to integrate as quick as possible, taking Spanish lessons every morning before training, but he walked into an almost impossible job: a club with huge expectations and one of the biggest budgets in the league, yet with the youngest squad and one short on leaders.

Neville soon acknowledged this by stripping Dani Parejo of the captaincy, believing the 26-year-old midfielder was not leadership material. At half-time in a game against Rayo Vallecano, Neville compelled Parejo to have the final say and rally the troops. His response must have fallen short, because four days later Parejo was on the pitch against Las Palmas without the armband, which was passed to striker Paco Alacer.

This backfired though when Paco Alacer ended the same game with an ankle injury, and none of the four club captains were on the pitch against Barcelona, so Shkrodan Mustafi was the temporary leader, but he quickly showed his unsuitability for the role by diving in on Lionel Messi and getting sent off.

After the game the German defender admitted "the players in the dressing room are in the s---".

There is one piece of good news for Neville, however: were the worst to happen, he would be welcomed back with open arms to his former job as Sky Sports' lead pundit on its Monday Night Football programme, which he quit two months ago.

It is understood nothing has changed from December, when Sky Sports managing director Barney Francis agreed to release Neville from his contract. Francis said at the time: "The door will always be open should he wish to return."